This proposal is to continue to develop and increase the participation of Harbor-UCLA Medical Center and affiliated institutions in all phases of the Children's Cancer Study Group. Clinical research protocols are developed in the Children's Cancer Study Group to investigate pertinent questions regarding the natural history, treatment and epidemiology of childhood cancer. These studies will be carried out by means of coordinated program with chemotherapists, surgeons, radiotherapists, and pathologists. One major goal of the Children's Cancer Study Group is to design and coordinate clinical investigations for various neoplastic disorders of children. These investigations include controlled clinical trials in leukemia and solid tumors of the childhood, evaluations of newly developed therapeutic agents, and studies of the effects of immunotherapy and immunosuppression.